Manufacture of bituminous roadways.



UNITED STATES PATENT OFFICE.

CLIFFORD RICHARDSON, OF NEW YORK,-N. Y.,

ASS IGNOR TO THE BARBER ASPHALT PAVING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF WEST VIRGINIA.

MANUFACTURE OF BITUMINOUS ROADWAYS.

- Applicgtion filed September 19, 1908. Serial No. 453,783.

To all whom it may c oncern:

, Be itknown that I, CLIFFORD Riemann soN, residing 1n New York, in the county of New York and State of N ew, York, have inyente'd certain new and useful Improvements in the Manufacture of Bituminous Road- 1 ways, whereof the following is a specification.

" terial.

ituminous roadways consist of a mineral aggregate, more or less perfectly cemented together by a bitui mnous cementing maupon the proper grading of the aggret no difficulty. in making an admirable bit-ulabor and curately grade and proportion the aggregate and mix it after heating with the bituminous .and care is estowe minous .roadway, dprovided sufficient time to secure accurate appli-. cation of t ese known rinci les. The difficulty arises from the act t lat to properly apply these principles-increasesthe expense of \the roadway to an extent which may be prohibitive. The various processes therefore which have been devised for themanufacture of such roadways are in the nature of compromises, and relate to methods by which, without too greatly increasing the expense for materials, a sufficient approximation may be reached to the correct grading, proportionment, mixing and compression of the materials to secure a practical result without prohibitory expense. These methods have varied fromtho'se which attempt'to accement and then spread and compress it/to those 1n which the bituminous material is poured over the surface of an im erfectly prepared aggregate or stone of uni orin size in the expectation that the cementing ma terial will penetrate or permeate the aggregate somewhat as grouting enters the joints of stone. 1

By my process at very moderate expense, I am enabled to prepare the material for a roadway from a carefully graded aggregate,

- and thoroughly combine'it with the pro er proportion of bituminouscement, an t1enspreadand compress it, without'heating the aggregate or using-a" volatile solvent.

The bituminous cementing material can only be rendered sufi'iciently fluid to mingle pJroperly with the aggregate by heating.

n er

3 v Specification of Letters'PateIit.

'lhe excellence of the roadway de' e proper proportionment of the all previously used conditions it is Patented June a, lace.

aryto heat the entire aggregate prior to its mcorporation with the hot cementing material. The expensive plant required to accomplish this, together with the cost of fuel and labor involved, and the haul of materials to and from the plant, are a large factor in the cost of the pavement.

I have discovered a process whereby a hot cement may be added on the spot where the work is being executed, to a cold graded aggregate containing fine material, and ex- 'cellent results secured, without heating the aggregate. 7

According to my invention I employ a mineral aggregate composed of two materials. One of these is What is commonly known as N o. 2 stone, that is to say, crushed stone from three-fourths of an inch to two I inches in size, of the type commonly used'in the construction of ,macadam roadways.

The other material consists of. finer crushed stone, known'as screenings, a large proportion of the particles of which are of a size to j-ustpass a three-eighths inch aperture, and ranging from this size to dust. The proper proportion. of thislatter size should be used to fill the voids in the first mentioned material. With these I combine a bituminous cement, especially prepared to afford proper viscosity and fluidity. I

I -mix a. given quantity of the large stone in a cold but dry state, with the bituminous cement. The mixing may be done in an ordinary binder mixer, and preferably in immediate proximity to the roadway, whichis beinglaid, for which purpose the mixer may be mounted as is theordinary portable hydraulic concrete mixer. T e quantity of the ocmenting material added to the large stone, is enough to thoroughly coat the stone, together with a certain excess, sufficient to thoroughly coat the fine material, which is subsequently added. The cementing inate- 'rial should be added at a temperature of from 200 to 250 degrees Fahrenheit. "'Aftr this mixing has been properly accomplished the finer part of the a gregate is added and mixing is continued til a substantially homo geneous mixture is Induced.. This mixture iscthen withdrawn cm the mixer, and laid I mation of dust.

-and compressed, upon any suitably prepared roadway, or foundation as a wearing surface. I thus produce a surface containing an aggregate which is sufficiently stable to carry travel combined with a bituminous cement which keeps out water and prevents the for- Although attempts have been hitherto made to add a hot bituminous cementing material to a cold mineral aggregate, such attempts have not succeeded without the use of a volatile solvent, because the cement has been added at once to the entire aggregate under which circumstances, I have found that the fine material tends to take up all of the cement so that little or none of it actually adheres to the large stone, but by adding the bituminous material in the first instance to the large stone, together with a sufficient excess and then, after thoroughly mixing, subseqluently adding the finer material, I secure, as have discovered, a very much more sat isfactory result.

Having thus claim 1 The process of preparing bituminous described my invention, I

paving material whichconsists in employing a mineral aggregate of two sizes, the one consisting of No. 2 stone and the other screenings from three-eighths of an inch to dust, the latter being proportioned to fill the voids of the former; adding to the large sized material while cold a hot bituminous cement in amount more than suflicient to coat the stone; thoroughly mixing; and then adding the finer material.

In testimony whereof, I have hereunto signed my name, at New York city this twelfth day of September 1908.

CLIFFORD RICHARDSON. Witnesses: V

C. T. BRYAN, J L. BRUssLAR. 

